1. Field of the Invention
This invention relates to novel crystals or anhydrous L-lysine monohydrochloride, termed .alpha.-crystals, and to a process for producing the same.
2. Description of the Prior Art
L-lysine is useful as a feed supplement, as a component in infusion solutions and in many other areas. It is usually commercially supplied in anhydrous form as a monohydrochloride salt.
A general process for the production of the anhydrous crystals comprises concentration of a solution of L-lysine monohydrochloride, followed by cooling to yield dihydrate crystals of L-lysine monohydrochloride. The dihydrate crystals are subsequently dried to form the anhydrate crystals. The drying of the dihydrate crystals is usually carried out at low temperatures, such as near 100.degree. C. or lower, under atmospheric pressure or preferably under reduced pressure. When amino acid crystals are dried at higher temperatures, for example at 120.degree. C. for 3 hours, the dried products commonly become slightly yellow or brown. Accordingly, their commercial value is lowered. Using this method, the commercial anhydrous L-lysine monohydrochloride powder occasionally hardens and conglomerates into a solid block when placed in a vinyl package, causing a large problem in its supply.